I agree, whenever you can do it is the best time to exercise. I have a very flexible schedule, which also means that my schedules changes a lot from day to day. So I end up working out at all different times, sometimes 5 AM, sometimes noon, sometimes 8 or 9 PM. My prefered time is probably mid-afternoon.
There are other factors to consider besides just the effect on your metabolism. I've learned the hard way that if I'm going to go running on a sunny day
, it's best to do it in the early morning or late afternoon/evening (otherwise I have to wear sunblock, sunglasses, and sometimes even a hat
). I try to go swimming during off-peak hours, otherwise the lanes are crowded and I'm constantly having to stop for people who are slower than me; it's just not as good a workout.
Likewise, I try to go to the gym during off-peak hours so I don't have to wait for the equipment I want.
I will say that when I get up early to exercises, it does feel great to have it out of the way!